Radial Diffusivity Values Research Articles

Diffusion tensor imaging revealed different pathological processes of white matter hyperintensities

BackgroundAlthough increasing evidence showed the correlations between white matter hyperintensities (WMHs) and cognitive impairment, the relationship between them is still modest. Many researchers began to focus on the variation caused by the heterogeneity of WMH. We tried to explore the pathological heterogeneity in WMH by using diffusion tensor imaging (DTI), so as to provide a new insight into the future research.MethodsDiffusion weighted images (DWIs) of the brain were acquired from 73 patients with WMH and 18 healthy controls, which were then modeled by DTI. We measured fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of white matter of the periventricular frontal lobe (pFL), periventricular occipital lobe (pOL), periventricular parietal lobe (pPL) and deep centrum ovales (dCO), and grouped these measures according to the Fazekas scale. Then we compared the DTI metrics of different regions with the same Fazekas scale grade.ResultsSignificantly lower FA values (all p < 0.001), and higher MD (all p < 0.001) and RD values (all p < 0.001) were associated with WMH observed in the periventricular frontal lobe (pFL) compared to all other regions with the same Fazekas grades. The AD of WMH in the pFL was higher than that of pPL and dCO, but the differences between groups was not as high as of MD and RD, as indicated by the effect size. In the normal control group, DTI metrics between pFL and other regions were not significantly different or less significant different. The difference of DTI metrics of WMH between pPL, pOL and dCO was lower than that of normal white matter, as indicated by the effect size.ConclusionDistinct pathological processes can be revealed by DTI between frontal periventricular WMH and other regions. These processes may represent the effects of severe demyelination within the frontal periventricular WMH.

Reduced white matter microstructure in bipolar disorder with and without psychosis.

Affective and psychotic features overlap considerably in bipolar I disorder, complicating efforts to determine its etiology and develop targeted treatments. In order to clarify whether mechanisms are similar or divergent for bipolar disorder with psychosis (BDP) and bipolar disorder with no psychosis (BDNP), neurobiological profiles for both the groups must first be established. This study examines white matter structure in the BDP and BDNP groups, in an effort to identify portions of white matter that may differ between the bipolar and healthy groups or between the bipolar subgroups themselves. Diffusion-weighted imaging data were acquired from participants with BDP (n=45), BDNP (n=40), and healthy comparisons (HC) (n=66). Fractional anisotropy (FA), radial diffusivity (RD), and spin distribution function (SDF) values indexing white matter diffusivity or spin density were calculated and compared between the groups. In comparisons between both the bipolar groups and HC, FA (FDR<0.00001) and RD (FDR=0.0037) differed minimally, in localized portions of the left cingulum and corpus callosum, while reductions in SDF (FDR=0.0002) were more widespread. The bipolar subgroups did not differ from each other on FA, RD, or SDF metrics. Together, these results demonstrate a novel profile of white matter differences in bipolar disorder and suggest that this white matter pathology is associated with the affective disturbance common to those with bipolar disorder rather than the psychotic features unique to some. The white matter alterations identified in this study may provide substrates for future studies examining specific mechanisms that target affective domains of illness.

Association between Uncinate Fasciculus Integrity and Agoraphobia Symptoms in Female Patients with Panic Disorder.

ObjectiveAlthough neural correlates of sub-clinical agoraphobia (AG) symptoms have been previously suggested, only a few studies evaluating structural changes of the brain have been conducted in agoraphobic patients with panic disorder (PD). We investigated and compared white matter (WM) micro-structural alterations between PD patients with AG (PD ＋ AG) and those without AG (PD − AG).MethodsOur study included 56 female PD patients, of which 25 were diagnosed with AG and 31 were diagnosed without AG. Diffusion tensor imaging was performed to investigate micro-structural changes in the WM tracts related to fronto-temporo-occipital areas (uncinate fasciculus, cingulum bundle, inferior longitudinal/fronto-occipital fasciculus, fornix column and body, and fornix/stria terminalis). All participants were subjected to the Anxiety Sensitivity Inventory-Revised (ASI-R), Beck Depression Inventory-II (BDI-II), and Albany Panic and Phobia questionnaires.ResultsThe fractional anisotropy values of the right uncinate fasciculus in PD ＋ AG were significantly lower than that of PD − AG and showed significant correlations with BDI-II and ASI-R total scores. Mean diffusivity and radial diffusivity values of the right uncinate fasciculus were significantly higher in PD ＋ AG as compared to PD − AG.ConclusionOur findings suggest that the uncinate fasciculus may be associated with AG symptoms in PD, possibly through demyelination. Our findings may contribute to the neurobiological evidence regarding the association between AG and WM structural changes in PD.

Diffusion Spectrum Imaging of Corticospinal Tracts in Idiopathic Normal Pressure Hydrocephalus.

Purpose: The purpose of this study was to measure the diffusion spectrum imaging (DSI) parameters of corticospinal tracts (CSTs) and evaluate diffusional changes in CSTs in patients with idiopathic normal pressure hydrocephalus (iNPH) by DSI.Methods: Twenty-three iNPH patients and twenty-one healthy controls (HCs) were involved in this study. Brain DSI data for all participants were collected through the same MR scanning procedure. The diffusion parameters measured and analyzed included quantitative anisotropy (QA), the isotropic diffusion component (ISO), general fractional anisotropy (GFA), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of corticospinal tracts.Results: The QA and ISO values of corticospinal tracts in iNPH patients were significantly lower than those in HCs (PLQA = 0.008, PRQA = 0.016, PLISO = 0.024, PRISO = 0.016). The mean MD, AD, and RD values in iNPH patients were significantly higher than those in HCs (PMD = 0.032, PAD = 0.032, PRD = 0.048,). No significant differences in GFA and FA values were noted between iNPH patients and HCs.Conclusion: Decreased QA and ISO values of corticospinal tracts were found in iNPH patients. Quantitative CST evaluation using DSI may lead to information that can improve the present understanding of the disease mechanism.

Alterations and Associations Between Magnetic Susceptibility of the Basal Ganglia and Diffusion Properties in Alzheimer's Disease.

This study adopted diffusion tensor imaging to detect alterations in the diffusion parameters of the white matter fiber in Alzheimer’s disease (AD) and used quantitative susceptibility mapping to detect changes in magnetic susceptibility. However, whether the changes of susceptibility values due to excessive iron in the basal ganglia have correlations with the alterations of the diffusion properties of the white matter in patients with AD are still unknown. We aim to investigate the correlations among magnetic susceptibility values of the basal ganglia, diffusion indexes of the white matter, and cognitive function in patients with AD. Thirty patients with AD and nineteen healthy controls (HCs) were recruited. Diffusion indexes of the whole brain were detected using tract-based spatial statistics. The caudate nucleus, putamen, and globus pallidus were selected as regions of interest, and their magnetic susceptibility values were measured. Compared with HCs, patients with AD showed that there were significantly increased axial diffusivity (AxD) in the internal capsule, superior corona radiata (SCR), and right anterior corona radiata (ACR); increased radial diffusivity (RD) in the right anterior limb of the internal capsule, ACR, and genu of the corpus callosum (GCC); and decreased fractional anisotropy (FA) in the right ACR and GCC. The alterations of RD values, FA values, and susceptibility values of the right caudate nucleus in patients with AD were correlated with cognitive scores. Besides, AxD values in the right internal capsule, ACR, and SCR were positively correlated with the magnetic susceptibility values of the right caudate nucleus in patients with AD. Our findings revealed that the magnetic susceptibility of the caudate nucleus may be an MRI-based biomarker of the cognitive dysfunction of AD and abnormal excessive iron distribution in the basal ganglia had adverse effects on the diffusion properties of the white matter.

Relationship of diffusion tensor imaging parameters with neurocognitive dysfunction in patients with Behcet’s disease

Behcet's disease (BD) is a chronic, multisystemic, relapsing-remitting, progressive inflammatory disorder with unknown etiology. The aim of the study is to investigate the white matter integrity and subclinical brain parenchymal involvement in Behcet's subjects by utilizing diffusion tensor imaging (DTI) and to correlate apparent diffusion coefficient (ADC), fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) values measured from the diverse distinct anatomic locations with the disease duration time and neurocognitive function test results. Thirty-five adults with Behcet's disease and 21 age-matched healthy controls were enrolled in this study. Neurocognitive functions of the patients were evaluated with the Brief Repetable Battery-Neuropsychological tests (BRB-N). In both groups, DTI metrics were calculated from 19 different locations in the brain. The association between the DTI parameters and disease duration time and neurocognitive function test results were investigated. In Behcet's disease, at the cingulum and the splenium of the corpus callosum (SCC), FA values were significantly lower compared with the controls (p = 0.0015, p = 0.003, respectively). The ADC values of the corona radiata and RD values of superior longitudinal fasciculus and SCC were significantly higher than the controls (p = 0.023, p = 0.028, p = 0.006, respectively). Significant negative correlations were found between the FA values of cingulum, genu of corpus callosum (GCC), posterior limb of internal capsule (PLIC) and disease duration time(r = -0.368; p = 0.029 and r = -0.337; p = 0.048 and r = -0.527; p = 0.001 respectively). All BD subjects performed significantly lower test scores on the spatial recall test (SPART) (p = 0.001). In addition, negative correlation was found between the MD values of the parietooccipital white matter and the selective reminding test (SRT) results (r = -0.353; p = 0.037). Our DTI study presented microstructural alterations in the neurocognitive-related areas and BRB-N test results even in patients without neurological symptoms which may imply insidious neurological involvement.

Influence of cytochrome P450 2D6 polymorphism on hippocampal white matter and treatment response in schizophrenia

Cytochrome P450 2D6 (CYP2D6) is expressed at high levels in the brain and plays a considerable role in the biotransformation and neurotransmission of dopamine. This raises the question of whether CYP2D6 variations and its impact on the brain can confer susceptibility to schizophrenia. We investigated the possible links among the CYP2D6 genotype, white matter (WM) integrity of the hippocampus, and the treatment response to antipsychotic drugs in Korean patients with schizophrenia (n = 106). Brain magnetic resonance imaging and genotyping for CYP2D6 were conducted at baseline. The severity of clinical symptoms and the treatment response were assessed using the Positive and Negative Syndrome Scale (PANSS). After genotyping, 43 participants were classified as intermediate metabolizers (IM), and the remainder (n = 63) were classified as extensive metabolizers (EM). IM participants showed significantly higher fractional anisotropy (FA) values in the right hippocampus compared to EM participants. Radial diffusivity (RD) values were significantly lower in the overlapping region of the right hippocampus in the IM group than in the EM group. After 4 weeks of antipsychotic treatment, the EM group showed more improvements in positive symptoms than the IM group. FAs and RDs in the CYP2D6-associated hippocampal WM region were significantly correlated with a reduction in the positive symptom subscale of the PANSS. Greater improvements in positive symptoms were negatively associated with FAs, and positively associated with RDs in the right hippocampal region. The findings suggest that CYP26D-associated hippocampal WM alterations could be a possible endophenotype for schizophrenia that accounts for individual differences in clinical features and treatment responses.

Importance of Pre-treatment Fractional Anisotropy Value in Predicting Volumetric Response in Patients with Meningioma Treated with Gamma Knife Radiosurgery.

BackgroundThe importance of pre-treatment Diffusion Tensor Imaging (DTI) parameters in determining the response to treatment after radiosurgery in patients with meningioma has not yet been clearly revealed.ObjectiveThis study was conducted to determine tumor volume changes in terms of radiological response in patients with meningioma treated with Gamma Knife Radiosurgery (GKR) and to analyze the relationship between Total Tumor Volume (TTV) and Diffusion Tensor Imaging (DTI) parameters. In addition, we investigated whether the response to treatment can be predicted by pre-radiosurgery DTI findings.MethodsFifty-four patients were assessed using MRI and DTI before and after GKR. Mean Diffusivity (MD), Fractional Anisotropy (FA), Radial Diffusivity (RD), and TTV of tumour were determined. Patients with 10% or more decrease in TTV after GKR were classified as group 1 and those with less than 10% decrease in volume or increase in volume were considered group 2. The relationships between MD, RD, and FA values and TTV were investigated.ResultsA decrease of 46.34% in TTV was detected in group 1 after GKR, while TTV increased by 42.91% in group 2. The lowest pre-treatment FA value was detected in group 1. In addition, after GKR, FA values showed a significant increase in group 1. MD and RD values increased in both groups after radiosurgery. There was a negative correlation between pre-treatment FA, RD, and MD values after radiosurgery.ConclusionDetection of low FA values due to the poor fiber content in meningioma before radiosurgery may be a guide in predicting the response to treatment. Further studies are required to have a better understanding of the relationship between pre- and post-treatment follow-up FA values and tumor volume in determining the efficacy of GKR in patients with meningioma.

Associations of subclinical autistic-like traits with brain structural variation using diffusion tensor imaging and voxel-based morphometry.

Previous case-control studies of autistic spectrum disorder (ASD) have identified altered brain structure such as altered frontal and temporal cortex volumes, or decreased fractional anisotropy (FA) within the inferior fronto-occipital fasciculus in patients. It remains unclear whether subclinical autistic-like traits might also be related to variation in these brain structures. In this study, we analyzed magnetic resonance imaging (MRI) data of 250 psychiatrically healthy subjects phenotyped for subclinical autistic-like traits using the Autism Spectrum Quotient (AQ). For data analysis, we used voxel-based morphometry of T1-MRIs (Computational Anatomy Toolbox) and tract-based spatial statistics for diffusion tensor imaging data. AQ attention switching subscale correlated negatively with FA values in the bilateral uncinate fasciculus as well as the bilateral inferior fronto-occipital fasciculus. Higher AQ attention switching subscale scores were associated with increased mean diffusivity and radial diffusivity values in the uncinate fasciculus, while axial diffusivity values within this tract show a negative correlation. AQ attention to detail subscale correlated positively with gray matter volume in the right pre- and postcentral gyrus. We demonstrate that individuals with higher levels of autism-spectrum-like features show decreased white matter integrity in tracts associated with higher-level visual processing and increased cortical volume in areas linked to movement sequencing and working memory. Our results resemble regional brain structure alterations found in individuals with ASD. This offers opportunities to further understand the etiology and pathogenesis of the disorder and shows a subclinical continuum perspective.

Subclinical post-traumatic stress symptomology and brain structure in youth with chronic headaches

Background/aimsPost-traumatic stress symptoms (PTSS) and chronic pain often co-occur at high rates in youth. PTSS may alter brain structure thereby contributing to headache chronicity. This study examined whether PTSS and altered limbic circuitry were associated with headache frequency in youth. MethodsThirty youth aged 10–18 years with chronic headaches and 30 age- and sex-matched controls underwent a 3T MRI scan. Volumes of the hippocampus and amygdala were obtained from T1-weighted images. Mean fractional anisotropy (FA, an index of white matter structure) axial and radial diffusivity values of the cingulum and uncinate fasciculus were extracted from diffusion-weighted images. Youth reported on their headaches daily, for one-month, and self-reported pubertal status, emotion regulation, adverse childhood experiences (ACEs) and PTSS using validated measures. Volumes of the hippocampus and amygdala and diffusivity values of the cingulum and uncinate were compared between patients and controls. Hierarchical linear regressions were used to examine the association between PTSS, subcortical volumes and/or diffusivity values and headache frequency. ResultsMean FA values of the cingulum were higher in patients compared to controls (P = 0.02, Cohen’s d = 0.69). Greater PTSS (P = 0.04), smaller amygdala volumes (P = 0.01) and lower FA of the cingulum (P = 0.04) were associated with greater headache frequency, after accounting for age, puberty, pain duration, emotion regulation, and ACEs (Adjusted R2 ≥ 0.15). Headache frequency was associated with increases in radial diffusivity (P = 0.002, Adjusted R2 = 0.59), as opposed to axial diffusivity (n.s.). ConclusionsPTSS, smaller amygdalar volume, and poorer cingulum structural connectivity were associated with headache frequency in youth, and may underlie headache chronicity.

Diffusion tensor imaging of oral carcinoma: Clinical evaluation and comparison with histopathological findings

PurposeThis study aims to assess the usefulness of diffusion tensor imaging (DTI) as a noninvasive method for the evaluation of histological grade and lymph node metastasis in patients with oral carcinoma (OC). Materials and methodsThirty-six consecutive patients with histologically confirmed OC underwent examination by 3-T MRI. DTI was performed using a single-shot echo-planar imaging sequence with b values of 0 and 1000 s/mm2 and motion-probing gradients in 12 noncollinear directions. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) maps were compared with histopathological findings. The DTI parameters were correlated with the histological grade of the OCs based on the World Health Organization grading criteria and the presence or absence of lymph node metastasis. ResultsThe FA values (0.275 ± 0.058) of OC were significantly lower than those of normal tongue, muscle, and parotid glands (P < 0.001 for all), and the MD, AD, and RD values (1.220 ± 0.149, 1.434 ± 0.172, and 1.019 ± 0.165 × 10−3 mm2/s, respectively) were significantly higher than their respective normal values (P < 0.001 for all). Significant inverse correlations with histological grades were shown for FA, MD, AD, and RD values in OC patients (r = −0.862, r = −0.797, r = −0.747, and r = −0.844, respectively; P < 0.001 for all). In addition, there was a significant difference in the FA values of metastatic and nonmetastatic lymph nodes (0.186 vs. 0.276), MD (0.923 vs. 1.242 × 10−3 mm2/s), AD (1.246 vs. 1.621 × 10−3 mm2/s), and RD (0.792 vs. 1.100 × 10−3 mm2/s; P < 0.001 for all). ConclusionsDTI may be clinically useful for the noninvasive evaluation of histological grade and lymph node metastasis in OC patients.

Evaluation of the effect of myelotomy on nerve function in rats with spinal cord injury by diffusion tensor imaging.

Spinal cord injury (SCI) is a severe central nervous system injury that can generally induce different degrees of sensory and motor dysfunction. To clarify the changes of diffusion tensor imaging (DTI) parameters after spinal cord myelotomy in rats with SCI. Eighteen Sprague Dawley (SD) rats were randomly divided into the Sham group (n=6), SCI group (n=6), and Mye group (n=6), respectively. The DTI values at 1, 3, 7, and 21 days after modeling were collected by magnetic resonance imaging (MRI). The spinal specimen at the injury site was collected on the 21st day for Nissl's staining to assess the changes in neurons. The fractional anisotropy (FA) values in both the SCI group and Mye group significantly decreased. In addition, the FA values between the two groups were statistically significant (P < 0.001). The apparent diffusion coefficient (ADC), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values all decreased and then increased (P < 0.001). Pearson correlation test showed that the ADC, MD, and AD values were positively correlated with the Basso Beattie Bresnahan (BBB) score. Nissl's staining showed a higher number of Nissl's bodies, and deep staining of Nissl's bodies in the Mye group, while the morphology of neurons was relatively good. The number of neurons in the Mye group was significantly higher after myelotomy compared to the SCI group (P < 0.001). The DTI parameters, especially ADC values, could non-invasively and quantifiably evaluate the efficacy of myelotomy for rats with SCI.

Longitudinal changes in cerebral white matter microstructure in newly diagnosed systemic lupus erythematosus patients

ObjectivesTo evaluate longitudinal variations in diffusion tensor imaging (DTI) metrics of different white matter (WM) tracts of newly diagnosed SLE patients, and to assess whether DTI changes relate to changes in clinical characteristics over time.MethodsA total of 17 newly diagnosed SLE patients (19–55 years) were assessed within 24 months from diagnosis with brain MRI (1.5 T Philips Achieva) at baseline, and after at least 12 months. Fractional anisotropy, mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity values were calculated in several normal-appearing WM tracts. Longitudinal variations in DTI metrics were analysed by repeated measures analysis of variance. DTI changes were separately assessed for 21 WM tracts. Associations between longitudinal alterations of DTI metrics and clinical variables (SLEDAI-2K, complement levels, glucocorticoid dosage) were evaluated using adjusted Spearman correlation analysis.ResultsMean MD and RD values from the normal-appearing WM significantly increased over time (P = 0.019 and P = 0.021, respectively). A significant increase in RD (P = 0.005) and MD (P = 0.012) was found in the left posterior limb of the internal capsule; RD significantly increased in the left retro-lenticular part of the internal capsule (P = 0.013), and fractional anisotropy significantly decreased in the left corticospinal tract (P = 0.029). No significant correlation was found between the longitudinal change in DTI metrics and the change in clinical measures.ConclusionIncrease in diffusivity, reflecting a compromised WM tissue microstructure, starts in initial phases of the SLE disease course, even in the absence of overt neuropsychiatric (NP) symptoms. These results indicate the importance of monitoring NP involvement in SLE, even shortly after diagnosis.

DTI parameters in neonates with hypoxic-ischemic encephalopathy after total body hypothermia

Background and purpose MR imaging provides means for discriminating different patterns of Hypoxic-ischemic encephalopathy (HIE) and may distinguish most severe cases from less severe but is unable to predict long-term outcome. Diffusion tensor imaging (DTI) offers information for a more complete characterization of HIE. The purpose of this study is to compare the modifications of DTI parameters in newborns one week and six months following total-body cooling to healthy controls. Methods Forty-seven cooled newborns were studied with MRI, 20 underwent follow-up at 6 months. 12 healthy newborns and nine children at 6 months were enrolled as control groups (HC). Inferior Longitudinal Fasciculus (ILF), Corpus Callosum Fasciculus (CCF), Corticospinal Tract (CST), Optical Tract (OT), Optic Radiation (OR) were generated in all subjects. DTI parameters were evaluated in basal ganglia (BG), thalamus (TH) and tracks. Statistical analysis was performed with MANOVA. Results In newborns HIE versus HC, there were significantly lower fractional anisotropy (FA) on OR and CST and higher axial diffusivity (AD), apparent diffusion coefficient (ADC) and radial diffusivity (RD) values on CST, BG and TH in HIE-N. At 6 months there were no significant grouping effects. The analysis showed a significant increase of FA, decrease of ADC, AD, RD after 6 months for HIE and HC. Conclusions We observed modifications of parameter values in HIE newborns vs HC; however normalization of values at 6 months suggests that changes of parameters cannot be considered early biomarkers for evaluation of therapeutic hypothermia in newborns with moderate HIE and normal conventional MRI.

White Matter Microstructure Underlies the Effects of Sleep Quality and Life Stress on Depression Symptomatology in Older Adults

Sleep complaints are the most prevalent syndromes in older adults, particularly in women. Moreover, they are frequently accompanied with a high level of depression and stress. Although several diffusion tensor imaging (DTI) studies reported associations between sleep quality and brain white matter (WM) microstructure, it is still unclear whether gender impacts the effect of sleep quality on structural alterations, and whether these alterations mediate the effects of sleep quality on emotional regulation. We included 389 older participants (176 females, age = 65.5 ± 5.5 years) from the 1000BRAINS project. Neuropsychological examinations covered the assessments of sleep quality, depressive symptomatology, current stress level, visual working memory, and selective attention ability. Based on the DTI dataset, the diffusion parameter maps, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), were calculated and normalized to a population-specific FA template. According to the global Pittsburgh Sleep Quality Index (PSQI), 119 poor sleepers (PSQI: 10∼17) and 120 good sleepers (PSQI: 3∼6) were identified. We conducted a two by two (good sleepers/poor sleepers) × (males/females) analysis of variance by using tract-based spatial statistics (TBSS) and JHU-ICBM WM atlas-based comparisons. Moreover, we performed a voxel-wise correlation analysis of brain WM microstructure with the neuropsychological tests. Finally, we applied a mediation analysis to explore if the brain WM microstructure mediates the relationship between sleep quality and emotional regulation. No significant differences in brain WM microstructure were detected on the main effect of sleep quality. However, the MD, AD, and RD of pontine crossing tract and bilateral inferior cerebellar peduncle were significant lower in the males than females. Voxel-wise correlation analysis revealed that FA and RD values in the corpus callosum were positively related with depressive symptomatology and negatively related with current stress levels. Additionally, we found a significantly positive association between higher FA values in visual-related WM tracts and better outcomes in a visual pattern recognition test. Furthermore, a mediation analysis suggested that diffusion metrics within the corpus callosum partially mediated the associations between poor sleep quality/high stress and depressive symptomatology.

Brain Diffusion Tensor Imaging Findings in Hashimoto's Thyroiditis.

Hashimoto's thyroiditis (HT) is a type of autoimmune thyroid disease. Diffusion tensor imaging (DTI) can evaluate microstructural brain involvement in various diseases. We aimed to investigate whether there were any DTI differences in patients with HT, and the relationship between DTI values and disease duration time and thyroid peroxidase antibodies (TPOAb) levels. We prospectively included 36 patients with HT (mean age 41.6 ± 13.8 years, range 18-64 years) and 18 age and sex-matched healthy control subjects (mean age 41.6 ± 13.1 years, range 18-63 years). All patients were euthyroid at the time of imaging. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values of 15 distinct neuroanatomical locations were measured and compared. FA values of the patients with HT were lower in cingulum, globus pallidus (GP), cerebellar white matter (CWM) than the control (P = .019, .002, and <.001, respectively). MD values of the CWM in patients were higher than the control (P = .008). AD values of patients with HT were lower in the cingulum, posterior limbs of the internal capsule, GP, and putamen (P = .038, .038, .030, and .045, respectively). RD values of cingulum and CWM in HT were higher than controls (P <.001 and P = .011, respectively). There was a negative relationship between the FA values of PLIC and a positive relationship between the MD values of the corona radiata and TPOAb levels were detected. The current DTI study presented microstructural changes in the neurocognitive-related areas that may be related to accompanying neurological findings in HT.

White matter microstructure and connectivity in patients with obsessive‐compulsive disorder and their unaffected siblings

We aimed to examine white matter microstructure and connectivity in individuals with obsessive-compulsive disorder (OCD) and their unaffected siblings, relative to healthy controls. Diffusion-weighted magnetic resonance imaging (dMRI) scans were acquired in 30 patients with OCD, 21 unaffected siblings, and 31 controls. We examined white matter microstructure using measures of fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Structural networks were examined using network-based statistic (NBS). Compared to controls, OCD patients showed significantly reduced FA and increased RD in clusters traversing the left forceps minor, inferior fronto-occipital fasciculus, anterior thalamic radiation, and cingulum. Furthermore, the OCD group displayed significantly weaker connectivity (quantified by the streamline count) compared to controls in the right hemisphere, most notably in edges connecting subcortical structures to temporo-occipital cortical regions. The sibling group showed intermediate streamline counts, FA and RD values between OCD and healthy control groups in connections found to be abnormal in patients with OCD. However, these reductions did not significantly differ compared to controls. Therefore, siblings of OCD patients display intermediate levels in dMRI measures of microstructure and connectivity, suggesting white matter abnormalities might be related to the familial predisposition for OCD.

Cerebral Micro-Structural Changes in COVID-19 Patients: An MRI-Based Preliminary Study

Background: Increasing evidence supported the possible neuro-invasion potential of SARS-CoV-2. However, no studies were conducted to explore the existence of the structural changes in the neurological system after infection. We aimed to identify the existence of potential brain structural changes related to SARS-CoV-2. Methods: In this prospective study, diffusion tensor imaging (DTI) and 3D high-resolution T1WI sequences were acquired in 48 recovered COVID-19 patients (60.42% male; mean age=47.81 ± 19.51) and 31 age-matched healthy controls (29.03% male; age=43.45 ± 13.6). Registered fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) were quantified for DTI, and a brain score system was introduced. Voxel-based Morphometry (VBM) and DTI metrics were compared using ANCOVA. Independent t-test and Spearman correlation were conducted to assess the relationships among imaging indices, brain scores and clinical information. Findings: COVID-19 patients had higher gray matter volumes (GMV) in hippocampus and Heschl’s gyrus, and higher white matter volumes (WMV) in corona radiata and tapetum. The left paracentral lobule was found to have significantly lower FA, higher MD, AD and RD values when compared with healthy controls. COVID-19 patients also had lower global MD and RD values, as well as lower brain scores of FA-GM, MD-GM, and MD-WM. MD values in the right corona radiata and external capsule were positively related to LDH level (r = 0.428, 0.417). Interpretation: Study findings reveal possible disruption to micro-structural and functional brain integrity in the recovery stages of COVID-19, suggesting neuro-invasion potential of SARS-CoV-2. Funding: This project was supported by Shanghai Natural Science Foundation (Grant No. 18ZR1405700), Youth Program of National Natural Science Foundation of China (Fund No. 81901697), Shanghai Sailing Program (Grant No. 18YF1403000), Shanghai Science and Technology Development (Fund No. 19511121204), Shanghai Municipal Science and Technology Major Project (No. 2018SHZDZX01) and ZJ Lab.Declaration of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Ethics Approval Statement: This was a prospective study, which was approved by the local ethics committee (No.20200616017) and written informed consent was obtained from each participant.

White matter fiber microstructure is associated with prior hospitalizations rather than acute symptomatology in major depressive disorder.

Eighty percent of all patients suffering from major depressive disorder (MDD) relapse at least once in their lifetime. Thus, understanding the neurobiological underpinnings of the course of MDD is of utmost importance. A detrimental course of illness in MDD was most consistently associated with superior longitudinal fasciculus (SLF) fiber integrity. As similar associations were, however, found between SLF fiber integrity and acute symptomatology, this study attempts to disentangle associations attributed to current depression from long-term course of illness. A total of 531 patients suffering from acute (N = 250) or remitted (N = 281) MDD from the FOR2107-cohort were analyzed in this cross-sectional study using tract-based spatial statistics for diffusion tensor imaging. First, the effects of disease state (acute v. remitted), current symptom severity (BDI-score) and course of illness (number of hospitalizations) on fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity were analyzed separately. Second, disease state and BDI-scores were analyzed in conjunction with the number of hospitalizations to disentangle their effects. Disease state (pFWE < 0.042) and number of hospitalizations (pFWE< 0.032) were associated with decreased FA and increased MD and RD in the bilateral SLF. A trend was found for the BDI-score (pFWE > 0.067). When analyzed simultaneously only the effect of course of illness remained significant (pFWE < 0.040) mapping to the right SLF. Decreased FA and increased MD and RD values in the SLF are associated with more hospitalizations when controlling for current psychopathology. SLF fiber integrity could reflect cumulative illness burden at a neurobiological level and should be targeted in future longitudinal analyses.

Microstructural Integrity of Peripheral Nerves in Charcot-Marie-Tooth Disease: An MRI Evaluation Study.

Charcot-Marie-Tooth (CMT) disease is diagnosed through clinical findings and genetic testing. While there are neurophysiological tools and clinical functional scales in CMT, objective disease biomarkers that can facilitate in monitoring disease progression are limited. To investigate the utility of diffusion tensor imaging (DTI) in determining the microstructural integrity of sciatic and peroneal nerves and its correlation with the MRI grading of muscle atrophy severity and clinical function in CMT as determined by the CMT neuropathy score (CMTNS). Prospective case-control. Nine CMT patients and nine age-matched controls. 3 T T1 -weighted in-/out-of phase spoiled gradient recalled echo (SPGR) and DTI sequences. Fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) values for sciatic and peroneal nerves were obtained from DTI. Muscle atrophy was graded according to the Goutallier classification using in-/out-of phase SPGRs. DTI parameters and muscle atrophy grades were compared between CMT and controls, and the relationship between DTI parameters, muscle atrophy grades, and CMTNS were assessed. The Wilcoxon Signed Ranks test was used to compare DTI parameters between CMT and controls. The relationship between DTI parameters, muscle atrophy grades, and CMTNS were analyzed using the Spearman correlation. Receiver operating characteristic (ROC) analyses of DTI parameters that can differentiate CMT from healthy controls were done. There was a significant reduction in FA and increase in RD of both nerves (P < 0.05) in CMT, with significant correlations between FA (negative; P < 0.05) and RD (positive; P < 0.05) with muscle atrophy grade. In the sciatic nerve, there was significant correlation between FA and CMTNS (r = -0.795; P < 0.05). FA and RD could discriminate CMT from controls with high sensitivity (77.8-100%) and specificity (88.9-100%). There were significant differences of DTI parameters between CMT and controls, with significant correlations between DTI parameters, muscle atrophy grade, and CMTNS. Level of Evidence 2 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:437-444.